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Noise level at base ISO pushed vs. higher ISO

thomas

New member
I'm confused… but that's not necessarily a bad thing here :)

I always thought an increase in ISO results in the same noise level as an underexposed capture pushed by the respective value.
So ISO50 underexposed by one stop and pushed in post by 1 EV is literally the same as shooting at ISO100.

Back in the days I did that test with my P45 and the results were as they were supposed to be.
Yesterday I did that test again. And as I was so perplexed about the results I did it again today under different conditions.

The underexposed shots at base ISO but pushed in Capture One by the respective values look much better than shooting at higher ISO.

The only explanation I can think of is shadow recovery and noise handling in Capture One has very much improved (my former test was done in C1 3.7 something).
Or has anyone a better idea about that? Has anyone discovered the same?

Here are the comparisons (same settings for all captures, no sharpening, noise reduction for luminance and color as written on the crops).
The difference at ISO50+1/ISO100 is not so obvious (in some areas of the capture it is) but at ISO200 it's a big difference.
Not only noise - all tonal transitions in the pushed base ISO shot look much better.
I ran that test with my P21+ as well - with the same results (at ISO100+1*/ISO200 even more obvious as with the P45).

*ISO100 is base ISO on the P21+
 
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Guy Mancuso

Administrator, Instructor
Thomas 5.0 the major improvement not talked about really in public but as a beta tester was the noise levels . They have been greatly improved along with the sharpening routines so not surprised to see that you are seeing these results. BTW I have the latest beta 5.1 and even more improvements and functions, should be out very soon too. Good news is they keep building a better bread box, I like that to be honest.
 

thomas

New member
Thomas 5.0 the major improvement not talked about really in public but as a beta tester was the noise levels . They have been greatly improved along with the sharpening routines so not surprised to see that you are seeing these results. BTW I have the latest beta 5.1 and even more improvements and functions, should be out very soon too. Good news is they keep building a better bread box, I like that to be honest.
Guy, thanks!
The images shown were processed through 5.1 Beta2. However I did not apply (user adjustable) noise reduction for luminance (nor the long exposure or surface setting or anything). My reading is that they improved the way NR works (and indeed works like charm!)... but if I do not apply NR (Lum.)... it must be a sophisticated way to recovery shadows.
Unless I am not mistaken... from now I always shoot at base ISO :D
 

Guy Mancuso

Administrator, Instructor
I have not played much with the new beta version and maybe I should try those Sensor plus shots again and see what's up
 

thomas

New member
I have not played much with the new beta version and maybe I should try those Sensor plus shots again and see what's up
maybe you should skip binning and shoot everything at base ISO :D
No... yes, it would be nice if could have a look at it. I think the newer backs have some stops "real" ISO (am not quite) sure... but the P45 (non plus) definitely not.
I thought the P21+ might have "real" ISOs... but from my findings it's probably just gained base ISO... in any case also with the the P21+ the pushed base ISO shots look better than setting the back to higher ISO (on the other hand the P21+ has really "nice" noise... still).
 

Guy Mancuso

Administrator, Instructor
I'm going to try some full res ISO 800 which I have been meaning to do anyway. Just need to get past the next couple days and I can concentrate on photography than. Lot's of stuff going on this week
 

dougpeterson

Workshop Member
Also what happens if you adjust color noise reduction settings to zero as well? The aggressiveness of those float as ISO changes as well and at higher settings can result in what feels like luminance noise reduction.
 

thomas

New member
Also what happens if you adjust color noise reduction settings to zero as well? The aggressiveness of those float as ISO changes as well and at higher settings can result in what feels like luminance noise reduction.
however it would apply to both the captures as I set the same Col.NR for both of the respective shots.
The values 12, 25, 45 for Col.NR are my settings for my P45's ISOs 50, 100, 200. And the truth is that I could even reduce Col.NR for the pushed shots - but not for the regular shots.

edit:
left pushed +2EV, right ISO200; col.NR zero
 
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s.agar

Member
Thomas, thanks for this experimentation. Very valuable. I use C1 V5, and will try the 800 ISO vs. your suggestion this weekend.
 

Professional

Active member
I will try that and see, i did shoot at ISO 100 and pushed it by 2 stops and it was fine, but i didn't shoot at ISO 400 to compare.
 

Jack

Sr. Administrator
Staff member
I've been doing this very thing for a few years since I discovered it was a very significant difference in M8 files --- ISO 640 pushed 2 was vastly superior to in cam 2500. It worked on my P45+ as well, saving a good 1/2 stop on noise at 400 and 800, however it seems to be a Kodak sensor trait as it doesn't appear to make much difference with my P65+ files.
 

thomas

New member
@ s.agar +Professional - I am looking forward to your findings - thanks a lot!

@ Jack - I'm glad you came to the same results!
Basically I can't imagine that the software goes beyond physical limits. So it could also be possible that my back produces too much noise at higher ISO settings.
But what I've seen from other P45s my copy seems to be rather good. Not only the ISO50 is superb, also ISO100 is quite good (keep in mind it's 2005 CCD technology). Too, my P21+ does exactly the same: pushed base ISO is better than shooting higher ISO. And as you found the same results I don't think it's a particularity of my P45 sensor.
As to your P65+ - maybe it's beacause the P65+ has "real" ISO?

BTW: I was interessted in this ISO thing because when you apply LCC based light falloff in Capture One you are pushing ISO at the edges (of course). Now there were some images in which the increase of light seemed to increase noise just a little bit, literally invisible, whilst in other examples the ISO push at the edges was more obvious. I couldn't draw any final conclusion from that and started to play around with this thing...
 

Professional

Active member
Just to be sure, do you push the exposure level for more stops for ISO? I mean if i shoot at ISO 100 and i move the exposure to +1 then it is like i push the ISO up to 200? or there is another way to push up the ISO?
 

thomas

New member
Just to be sure, do you push the exposure level for more stops for ISO? I mean if i shoot at ISO 100 and i move the exposure to +1 then it is like i push the ISO up to 200? or there is another way to push up the ISO?
this way:
- shoot at ISO50 for a correct exposure, say, f8 + 1/30''
- shoot at ISO50 and underexpose 1 stop, i.e. at f8 + 1/60''
- shoot at ISO50 and underexpose 2 stops, i.e. at f8 + 1/125''
- shoot at f8 + 1/60'' and set the back to ISO100 (for correct exposure)
- shoot at f8 + 1/125'' and set the back to ISO200 (for correct exposure)


for the comparision:

- push the 1 stop underexposed ISO50 shot by 1 stop in the RAW software and compare it to the ISO100 shot
- push the 2 stops underexposed ISO50 shot by 2 stops in the RAW software and compare it to the ISO200 shot
 

Professional

Active member
this way:
- shoot at ISO50 for a correct exposure, say, f8 + 1/30''
- shoot at ISO50 and underexpose 1 stop, i.e. at f8 + 1/60''
- shoot at ISO50 and underexpose 2 stops, i.e. at f8 + 1/125''
- shoot at f8 + 1/60'' and set the back to ISO100 (for correct exposure)
- shoot at f8 + 1/125'' and set the back to ISO200 (for correct exposure)


for the comparision:

- push the 1 stop underexposed ISO50 shot by 1 stop in the RAW software and compare it to the ISO100 shot
- push the 2 stops underexposed ISO50 shot by 2 stops in the RAW software and compare it to the ISO200 shot
Ah cool, i will do that ASAP.
 

Jan Brittenson

Senior Subscriber Member
What do you mean by "pushing" during PP? Generally, reducing exposure and increasing gamma often looks better. It shoulders the highlights, which is highly noticeable, and pays for it in the shadows, which may not be as noticeable. NR can be selectively applied to the bottom end, without really affecting the overall image appearance much. Depends on where you're going and the look you're after. IMO.
 

Jack

Sr. Administrator
Staff member
Jan,

to push we use the "exposure" slider in RAW not the "Brightness" slider or Curves. The main difference is the exposure slider affects the entire image linearly across the histo, where the Brightness protects the end points.
 
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